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Re: synthetic and conventional oil question



On Sun, 25 Nov 2001 14:52:41 -0800 "Dave Ewing" <rabbit16v@prodigy.net>
writes:
> Why 15w-40 or 20w-50?  You guys better back this stuff up because 
> there is NOTHING wrong with 5w or 10w and you just told this guy that
he has 
> to run 15w or 20w.  Think about this stuff people!!!  Besides, most 
> synthetics are thiner than regular oil so why would you recomend a
thicker oil?  He 
> never said where he lives so he could live in South Florida where you'd

> want to run a lighter oil for quicker oil pressure.  Just my opinion!!
> 
> Dave

If Victor Farren was in South Florida, he should definitely run 15-40 or
20W50 in the winter, and SAE30 or 40 for the rest of the year.

Victor Farren lives in the Mid-Atlantic area, and with the warm temps
we've been having, 10w30 AND 10w40 is only recommended up to 50ºF,
according to the Volkswagen Owner's manual, according to the Volkswagen
Owner's manual.

15W40 is recommended down to 5ºF (only 8ºF higher than 10w30 and 10w40)
and up to 85ºF, according to the Volkswagen Owner's manual...

"Multi viscosity oils work like this: Polymers are added to a light
base(5W, 10W, 20W), which prevent the oil from thinning as much as it
warms up. At cold temperatures the polymers are coiled up and allow the
oil to flow as their low numbers indicate. As the oil warms up the
polymers begin to unwind into long chains that prevent the oil from
thinning as much as it normally would. The result is that at 100 degrees
C the oil has thinned only as much as the higher viscosity number
indicates. Another way of looking at multi-vis oils is to think of a
20W-50 as a 20 weight oil that will not thin more than a 50 weight would
when hot. Multi viscosity oils are one of the great improvements in oils,
but they should be chosen wisely. Always use a multi grade with the
narrowest span of viscosity that is appropriate for the temperatures you
are going to encounter. In the winter base your decision on the lowest
temperature you will encounter, in the summer, the highest temperature
you expect. The polymers can shear and burn forming deposits that can
cause ring sticking and other problems. 10W-40 and 5W-30 require a lot of
polymers(synthetics excluded) to achieve that range. This has caused
problems in diesel engines, but fewer polymers are better for all
engines. The wide viscosity range oils, in general, are more prone to
viscosity and thermal breakdown due to the high polymer content. It is
the oil that lubricates, not the additives. Oils that can do their job
with the fewest additives are the best. Very few manufactures recommend
10W-40 any more, and some threaten to void warranties if it is used. It
was not included in this article for that reason. 20W-50 is the same 30
point spread, but because it starts with a heavier base it requires less
viscosity index improvers (polymers) to do the job."

Copied and pasted from: 
http://www.rconcepts.com/beard/dragnet/drag/oilinfo.html

Peter - <http://thescirocco.com> - Discount Techtonics, Peloquin LSD,
Autotech-Quaife USA, Ronal USA, Motorworks, & Magnecor Dealer -  Bear, DE
19701                
'79 Scirocco 16V 25 049
'83 GTI 37 505
'84.5 Scirocco 42 133
'84 GTI 63 348  - SciRollers: '79 70 900, '84 Black, '88 Red - 

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